1. Field of the Invention
The present invention relates to a microprocessor-controlled gas appliance, in general, and to a microprocessor-controlled residential gas range, in particular.
In the present invention, a microprocessor is used to control a burner valve and other operating systems of the residential gas range. The microprocessor is also used to provide a number of different features. For example, a temperature sensor is used to monitor cooking pan or pot temperature for precise control and temperature ramping. Provision is made for ignition and flame-proving. It is contemplated that there will be a host of alarms to take care of gas system failure and gas leaks. Carbon monoxide, combustibles, occupancy and smoke detectors are also included.
2. Background Art
In general, gas appliances have not kept pace with their electrical counterparts in terms of the extended functionality afforded by the use of microprocessor-based control. One reason for this is the lack of an inexpensive and reliable microprocessor-controllable gas valve that can be incorporated into such devices as clothes dryers, commercial cooking equipment, warm air furnaces and domestic cooking appliances.
In clothes dryers, the ability to modulate the gas flame would add the benefit of shorter drying cycles. With regard to commercial cooking equipment, modulation of the gas flame has the advantage of tighter control of temperature in such appliances as ovens and deep-fat fryers. With regard to warm air furnaces, a controllable gas valve would form the heart of an advanced control system.
Finally, in the area of domestic cooking appliances, such as gas ranges, there is a need for gas flame modulation as well as enhanced functionality of the range. At the present time, residential gas ranges do not take advantage of the convenience, flexibility and safety possible through advanced microprocessor-based technologies.
Most cooking appliances produced today include more than one cooking station in the same appliance, often with several functions being available for one or more of the different cooking stations. For example, a single cooking appliance may include four burners or other surface heating elements at one cooking station, and a conventional oven at a second. The oven may be capable of baking, broiling, as well as other functions.
In order to enter cooking control information such as the temperature and the time for each of the various cooking functions of such multi-function appliances, a fairly complicated control panel has conventionally been required. Typically an analog control knob for entering times and temperatures is associated with each group of cooking station controls. Normally, only a frequent user of the appliance is able to enter the more common cooking control information for the oven without consulting an instruction book.
U.S. Pat. Nos. 4,341,197 (Butts) and 4,454,501 (Butts) relate to a control arrangement for a multi-function cooking appliance which has a plurality of cooking stations. The control arrangement includes a control panel having a group of keys for entering control information for the stations and functions of the cooking appliance and a prompting device for messages which assist in entering the control information. These two patents disclose a control system in the context of an electric range and, therefore, offer no disclosure or insight into a microprocessor-based residential gas range employing computer-controlled gas flow valves.
U.S. Pat. No. 4,492,336 (Takata et al) relates to an automatic temperature control system employing a gas burner. As part of the control system is a solenoid valve and a proportional control valve that is adjusted through a temperature sensed by a temperature sensor and processed by dedicated electronic circuitry.
U.S. Pat. No. 4,391,265 (Chen) relates to a gas range that is controlled through a keypad or touch plate and includes a motor driven valve that contains a plurality of channels of different sizes. The motor driven valve is placed within a gas line to adjust the amount of gas directed to a burner of the gas range.
U.S. Pat. No. 4,125,357 (Kristen et al) relates to an electronic control system and a gas range for controlling gas burners in four ways. The control system accomplishes the following four functions: (1) initial ignition of the gas, (2) continued combustion of the gas, (3) time rate averaging at which gas is burned, and (4) temperature maximization of the combustion chamber.
U.S. Pat. No. 4,505,300 (Jaegar) relates to a control valve apparatus including a modulating valve for controlling the amount of gas or fluid passing through a line. The valve accomplishes modulation through the use of a multiplicity of valve seats, springs and sliding elements.
U.S. Pat. No. 3,852,728 (Flagg, Jr.) is cited merely to show the incorporation of a warning device to indicate that the burners of an electric range are hot.
As pointed out in the Kristen et al patent, in the general field of gas burners, ignition safety devices and devices for effecting a maximum temperature limitation, typically take the form of separate devices for each separate task. In addition, yet another separate device is generally employed for regulating the average energy output of the unit. Some ignition safety and flame monitoring devices employ photoelectric cells and ionization sensors for checking the flame. Other devices operate with a bi-metallic element which operates in conjunction with a pilot flame. In still other cases, gas valves may be directly driven by thermo-sensitive elements. Typically, the maximum temperature control function is performed by rod expansion switches or by bi-metal switches. The average energy output of the burner is typically controlled by bi-metal switches or use liquid expansion switches or gas expansion switches, and with apparatus for operating the burner on a time-pulsed basis, independently of the burning chamber temperature.
Thus, there is a need for a gas appliance incorporating a microprocessor-controlled valve for controlling each burner to achieve specific setpoints versus time. There is also a need for a gas appliance which incorporates a temperature sensor used to monitor the temperature of interest, such as cooking pan or pot temperature in the case of a gas range. Further, there is a need for a gas appliance that makes use of gas sensing to operate alarms in case of system failures and gas leaks. There is also a need for gas appliances which are capable of interaction with microprocessor-based systems outside of the appliance itself. The present invention is directed toward filling these needs.